Planetary high-speed printer

ABSTRACT

The printer is constructed with a movable printing head having a plurality of rotatable planetary-type wheels mounted to protrude slightly through the outer rim of the printing heads. The planetary-type wheels are mounted in a plane parallel to the plane of the printing heads and their axes are parallel to the axis of the printing heads. The planetary-type wheels are geared to a drive system that moves the printing heads such that they rotate with the precise surface velocity of each printing head but in an opposite direction. Each planetary-type wheel is provided with a discrete number of identical raised-type faces separated by the precise dimension desired for character spacing on the printed page. In one embodiment of the invention, the printing paper is curved in an arc around a cylindrical printing head close to or in contact with the type wheels. In another embodiment of the invention the paper is held flat. The length of the paper is parallel to and moves along the axis of the printing heads. Individual forcing means are provided at each character position to press the paper into printing contact with the rolling-type face. The desired character may then be printed at each occurrence on a line by merely energizing a forcing means as a type wheel moves sequentially to each character position on the paper strip. Electronic control means are provided for controlling the individual forcing means as a function of the desired character printing position on the paper.

United States Patent 72] Inventor Richard A. Hartley 4225 Ethel Ave., Studio City, Calif. 91604 [21] Appl. No. 837,201

[22] Filed June 27, 1969 [45] Patented Jan. 11, 1972 [54] PLANETARY HIGH-SPEED PRINTER 8 Claims, 12 Drawing Figs.

[52] US. Cl..... 101/93 [51] Int. Cl B411 [50] Field of Search 101/93 C,

Primary ExaminerAntonio F. Guida Attorney-Reagin & Braunstein ABSTRACT: The printer is constructed with a movable printing head having a plurality of rotatable planetary-type wheels mounted to protrude slightly through the outer rim of the printing heads. The planetary-type wheels are mounted in a plane parallel to the plane of the printing heads and their axes are parallel to the axis of the printing heads. The planetarytype wheels are geared to a drive system that moves the printing heads such that they rotate with the precise surface velocity of each printing head but in an opposite direction. Each planetary-type wheel is provided with a discrete number of identical raised-type faces separated by the precise dimension desired for character spacing on the printed page. In one embodiment of the invention, the printing paper is curved in an are around a cylindrical printing head close to or in contact with the type wheels. In another embodiment of the invention the paper is held flat. The length of the paper is parallel to and moves along the axis of the printing heads. individual forcing means are provided at each character position to press the paper into printing contact with the rolling-type face. The desired character may then be printed at each occurrence on a line by merely energizing a forcing means as a type wheel moves sequentially to each character position on the paper strip. Electronic control means are provided for controlling the individual forcing means as a function of the desired character printing position on the paper.

PATENIEB we 1 1 SHEET 2 BF 6 INVENTOR F/(WAFQ ,4. #APH 6) BY 1/ t 1 D ad/ @TTORNEY BACKGROUND OF THE INVENTION Machines used in the data processing art are under continual development in order to improve their speed. The printout equipment presently used in conjunction with these machines severely limits their useful output. Attempts have been made to closely mate the printers printing speed to that of the data processing machine. One such attempt by the present inventor appears in U.S. Pat. No. 2,776,618 entitled Printing Cylinder for High Speed Printing Systems". The printer of that patent provided a skewed-type printing cylinder in which the cylinder can be continuously rotated. The printing medium (paper), however, is advanced intermittently.

Another patent of interest to show the state of the prior art is U.S. Pat. No. 2,210,021, entitled Printing Means for Cash Registers, Accounting, and the Like Machines" by E. Breitling et al. The device of that patent uses type wheels which are used intermittently but not as part of a planetary system. FIGS. 4, 4A and 11 of that patent are of interest for their showing of a rachet actuated system using cylinders which rotate with respect to a central gear.

US. Pat. No. 2,926,602 entitled Automatic Printer" by D. N. MacDonald et al., is of interest for its showing of a helixtype wheel. The type wheel is continuously rotated and advanced across the face of the printing paper to bring all the type faces into alignment with a line on the paper during one revolution of the type wheel.

In US. Pat. No. 2,997,542 entitled High Speed Tele-Printer" by J. lnove, there is disclosed a printer which uses a plurality of planetary-type wheels which rotate in a direction opposite to the direction of the printing head to provide a static character at the printing point. Additionally, each type wheel carries three type faces with the face to engage the printing point being selected by rotating the internal gear of the planetary system to one of three prescribed positions. Only one character of a type can be printed per revolution of the print head for the device of that patent, making this a very low speed printer.

Another patent of interest is U.S. Pat. No. 3,205,305 entitled Planetary Recording Apparatus by C. H. Clark et al. In that patent there is disclosed a plurality of planetary-type cylinders which are rotated in a direction counter to the major printing head to maintain the type static at the printing point. Only one type character is in alignment with the printing point at any one time and there is only one printing point. In FIG. 18 of that patent there is shown a number of type faces aligned with a corresponding number of printing points but the points are all along a line which describes a single tangential point of the planetary cylinder.

The final patent of interest is US. Pat. No. 3,141,402 entitled Planetary Type Body for Printer" by B. Howard. In that patent a plurality of planetary-type wheels are provided wherein the character face always remains parallel to the paper and the plane of the hammer. Correct hammer actuation is essential for this device, otherwise the characters will not print on a straight line. For contact in applicants device, the type is rolled into contact with the paper and forcing means to provide straight line printing with no smear and complete character printing. An additional limitation of the referenced device is that only one tangential point of one printing cylinder is in position with the paper at any one time.

From the above discussion of the prior art printers, it can be seen that their speed leaves a little to be desired. It would therefore be highly advantageous to have a printer which in one revolution of the printing head could print out completely all the characters necessary for that line. The speed of such a printer would, therefore, be extremely high regardless of the length of the lines. Such a printer would indeed be a match for present day data processing machines and would also be the next generation of printer. Applicant's inventive high speed printer is just such a device.

SUMMARY OF THE INVENTION The printer is comprised of a movable printing head having a plurality of rotatable planetary-type wheels mounted with their axis of rotation parallel to the rotation axis of the printing head. Means are provided for moving the printing heads in one direction and for rotating the type wheels in an opposite direction at the precise surface velocity of the printing heads. In one embodiment of the invention, a cylindrical printing head is used with a plurality of type wheel positioned around the circumference of the cylinder and a thin sheet of recording medium such as paper, held curved in an arc tangential with at least two of the type wheels. Individual forcing means are positioned behind the recording medium in line with each character position of a line. Electronic control means are provided for activating the individual forcing means when a desired type wheel passes across a desired character position. In operation, for example, the type wheel having the letter e" thereon could have the paper forced against it to cause printing at a number of character positions as it sequentially moves across the character positions on the paper. The total line is printed out by having each type wheel sequentially passed over each character position in a line with forcing (printing) taking place once per character position except for space positions. In a preferred embodiment, a plurality of type wheels are rolling across the paper simultaneously printing out their respective character in the desired character position. At the end of one line of printing, the paper is quickly advanced on line space. It may be necessary in some applications to allow the printing head to make a second revolution to provide time for the paper to advance. In a second embodiment of the invention, the paper is advanced at a steady rate and the printing-type wheels are positioned in a helix pattern on the printing head. The pitch of the helix pattern is approximately on line spacing for a complete revolution of the printing heads. This particular configuration of the type wheels allows the paper to be continuously moved with respect to the printing heads while still providing a straight line print out of characters.

The impulse type paper advance may be used in those applications which require a lower speed printer.

In still another embodiment of the invention, the printing heads are formed into a chain-type arrangement having an oval path. The paper or printing medium is then positioned along the flat surface or surfaces of the oval path with printing being accomplished in an identical manner as with the cylindrical printing head.

Depending upon the speed desired, it may be desirous to provide a memory means for reading and storing a complete line of information which may be in digital form or which is transferred into digital form. The memory means under synchronized control applies the stored character signals to the correct impact means in coordination with the position of the desired type wheel. Each planetary-type wheel has a plurality of raised identical characters positioned around the periphery of the wheel at spaces corresponding to a character space on the paper. In the preferred embodiments, the character faces can be curved to correspond to the curvature of the wheel and/or the paper. This curvature allows the character to be rolled onto the paper at the exact character position without critical timing of the impact means. It is also practical to provide two or more rows of characters per type wheel in order to print out two or more lines of information simultaneously.

Accordingly, it is an object of the present invention to provide a novel printer.

It is another object of the present invention to provide a printer which will print out one complete line of information regardless of the length of the line with one revolution of the printing head.

It is another object of the present invention to provide a printer having precise character spacing.

It is another object of the present invention to provide a printer which will print each character in a line directly on the line without smearing and need forcritical forcer timing.

It is another object of the present invention to provide a printer which is capable of printing two or more lines of information simultaneously.

Another object of the present invention is to provide a printer which is compatible with the speeds of present day data processing machines.

These and other objects of the invention will become more clear when taken in conjunction with the following description and drawings wherein like numbers indicate like parts and which drawings form a part of this application.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a projection view, partially in cutaway, of one embodiment of the invention.

FIG. 2 is a sectioned view of a second embodiment of the invention.

FIG. 3 is a block diagram of an electronic control system which may be used with the embodiments of the invention.

FIG. 4 is a plan view of one type of forcer which may be used with the printer.

FIG. 5 is a top sectioned view taken along the section lines 5-5 of FIG. 2.

FIG. 6 is a sectioned view of a second embodiment of the invention showing the type wheels with double rows of type skewed along a helix line on the printing head.

FIG. 7 is a sectioned view showing a second type of forcer means which may be substituted for that shown in FIG. 5.

FIG. 8 is a sectioned view taken along the section lines 88 of FIG. 7.

FIG. 9 is an exploded view of a portion of the forcing means of FIGS. 7 and 8.

FIG. 10 is a top view of another embodiment of the inventron.

FIG. 11 is a sectioned view taken along the section lines llll of FIG. 10.

FIG. 12 is a partially sectioned view of a planetary-type wheel which may be used with the embodiment of FIG. I0.

DESCRIPTION OF THE INVENTION Referring to FIG. 1, a cylindrical printing head 10 is mounted for rotation about an axis defined by bearings 24 and 25. A shaft 21 connected to a source of power (not shown for purpose of clarity) rotates a coaxial gear 26 by means of gears 22a thru 22:1 in gear box 23. Coaxial gear 26 is rotatably mounted on shaft 21. A plurality of planetary-type wheels 12 are rotatably mounted to the printing head 10 by means of bearings 18. The axis of rotation of the planetary-type wheels 12 is parallel to the axis of rotation of the printing head 10. The planetary-type wheels extend slightly from the periphery of the printing head. Each planetary wheel 12 has a plurality of discrete, raised type faces 13 of the same type, spaced one character space from each other around the periphery of the wheel. To make a complete typewriter type printer, 82 type wheels are needed. For a minimum tabulating printer, 40 type wheels are sufficient. The invention will be described in terms of the 40 minimum number type wheel embodiment for simplicity. A drive gear 16 is affixed to each planetary-type wheel 12. The coaxial gear 26 rotates drive gear 16 and planetarytype wheel 12. The radius of gears 26 and 16 in conjunction with the gears of gear box 23 are chosen such that planetarytype wheels 12 rotate in an opposite direction to the direction of rotation of the printing head 10 with the precise surface velocity of the printing head. The easiest mechanization for constructing this planetary printer would be to make gear 16 mesh with an internal gear whose pitch line was as the same radius as the printing surface of the type faces 13. But the recording sheet 30 must be in this position so gear 26 is provided to mesh with gear 16 on the inner pitch line. Since gear 26 does not have the same number of teeth as an internal gear would have, it must be rotated to compensate so that the type faces have no motion relative to the recording sheet. Bearings 18 are supported in a cylindrical frame 17 which is rotated by shaft 2| through a press fit web 39. Gear 26 must be positioned on the inner circle because the recording sheet 30 is positioned on the outer surface of the type wheel surface. Recording sheet 30, which may be a sheet of paper, is curved in an are by means of a paper guide 33 to place the surface of the paper in close proximity to or in close contact with a group of the planetary-type wheels 12. The paper is thereby held tangent to at least two of the cylinders at a noncommon tangent point. A takeup reel 31 receives the paper after it has been printed upon. A drive platen 32 having sprockets 35 thereon may be used to advance the paper by engagement with holes 34 positioned along the length of the paper at both edges. Other means for advancing and positioning the paper may be used effectively and are well known to persons skilled in the art. The paper is advanced one line space after each line is printed. In other embodiments of the invention the paper is advanced at a constant rate. Forcing means 40 are positioned behind the paper to force the paper into printing contact with a desired character face on a planetary-type wheel when the character face is in correct line printing position with respect to the paper. The operation and construction of the forcing means will be discussed in more detail later.

Referring now to FIG. 2 along with FIG. I, the electronic control system for the printer is comprised in part of a stationary cylindrical magnetic memory 70 affixed to the inner wall of the printing case 50 and symmetrically positioned about the rotation axis of the printing head 10. A magnetic write head stack 71 is affixed to the rotating head 10 along a line which is parallel to the axis of rotation of the printing head. The write head stack is comprised of a plurality of stacked magnetic write heads 74 which correspond in number to the number of planetary-type wheels. The stack 71 is positioned in close proximity to the stationary memory such that each write head 74 has an individual recording track around the inner periphery of the memory. The write head stack 71 is used to record an input control message on.the stationary memory 70 at each character position.

An erase head 72 precedes the write head stack 71 to erase the stationary memory 70 clean, ready for writing, after each revolution of the printing head. This particular positioning of the erase and write heads 72 and 71 respectively creates a gap between the first and the last planetary-type wheel to allow a sufficient time space for the advancement of the paper one line space before the first type wheel is again ready to print. One read head 73 is mounted in the rotating head structure under each type wheel. Each head is positioned axially along the rotation axis of the printing head to read the track assigned to that type wheel, and only that one track. While the heads are normally directly under their respective type wheels, their positions may be shifted around the circumference of the head structure to compensate for any delays in operating time in the circuitry and forcing means. Thus, whenever a read head 73 detects a signal recorded on its track, the forcing means for the corresponding character position is energized to print the designated character.

Referring now to FIG. 3 in conjunction with FIG. 2, the elements falling within the dotted blocks are mounted on the rotatable printing head 10. The remaining elements are affixed to a reference frame such as the printer case 50. Assuming that the printer is to receive information from a computer in the form of a six bit binary code, there is provided six C" shaped coaxial pairs of rotary transformers 125. One-half of each transformer is mounted on the printing head 10 with the other half mounted to the reference frame. The rotary transformers may be replaced by six ordinary slip-rings with contacting brushes for use at lower speeds. Such brushes have inherent maintenance and operation problems which are well known in the art. The six pulses conducted into the rotating system define the character that is to be printed in each character position. They in turn are applied to a six bit input to 40 line matrix output decoding network. The 40 output lines are connected directly to the stack of 40 writing heads 7 I.

While the individual pulses generated by the read heads 73 can determine the printer force timing, it is better to rely upon a common character clock to provide precise timing for all of the printing forcers. This is accomplished by providing a narrow magnetic memory band 80A of, for example, magnetic film, on the rotatable printing head 10. One timing bit is recorded on the magnetic band 80A corresponding to each character space of the recording medium and a printing forcer. A read head 81A mounted to the stationary frame 50 receives a character pulse when the bit passes in front of the head. In this manner when a timing pulse is received by a gate along with a read head pulse indicating that a character is to be printed in that spot, the forcer for that character position is actuated. Two additional clock heads 81B and 81C, identical to heads 81A may be positioned below head 81A, with their own memory strips 808 and 80C to provide line start and stop clock pulses to the computer which causes the computer to start to feed information to the six rotary transformers 125.

The computer will continue to feed information to the write head stack 71 until the line-stop clock pulse is received signalling the end of the line. The stop pulse then inhibits the receipt of information from the computer until a start pulse is received. In this embodiment which does not have a skewed head, an additional clock head 81D and memory track 80D can be used to provide a paper advance signal for advancing the paper one line width at the end of one line of printing.

The 40 channel write head stack 71, as previously discussed, writes on the stationary memory 70. The written code on the stationary 70 is read by 40 read heads 73 (one per type wheel). The outputs from the read heads are connected individually to 40 amplifiers 128. The output of amplifiers 128 are coupled to a like number of C shaped transformers 102. Transformers 102 are electrically coupled to corresponding C" shaped transformers 104 which are coaxial with transformers 102. Transformers 102 and 104 form a rotating magnetic pulse commutator 100. The transformers 104 are positioned with their laminations precisely positioned on the radius vector of the corresponding character position on the paper. The mating commutator elements 102 are precisely positioned on the radius vector of the corresponding type wheel. The mating commutator elements need not be on their corresponding radius vector literally, but they must have this relationship to each other. The two commutator elements are mounted in a plane so that when one of the type wheel transformers 102 is energized by an electrical pulse, when it is just opposite a character, the resulting magnetic flux is conducted to the transformer 104 of the stationary unit and induces a voltage pulse therein, the voltage pulses are coupled to one or more respective amplifiers 129. The output from each amplifier is fed to an AND-gate 130 which also receives the timing pulse from clock character head 81A. When the two pulses are received simultaneously an activation signal is fed to a forcer 40 causing a character to be printed out.

Electrical power can be brought into the rotatable printing head by means of the slip ring and brush assemblies 75.

Referring now to FIGS. 4 and 5, the forcing means 40 is comprised of a number of identical printing actuators (forcers), there being one for each character position in a printed line. A rigid frame 43 is fixed to the printing frame 50. The frame supports two dogleg levers 42 and 45 which are connected to a compliant printing pad 41. The pad 41 is slidably mounted to the frame 50. Electromagnets 44 are positioned to draw the dogleg levers 42 and 45 upward, thereby extending their effective length, holding the printing pad 41 rigid against the paper and in turn the paper against the type face 13 as it rolls across the paper. An adjusting screw 46 is provided to place the pad 41 into correct space alignment with the paper. The return spring 47 pulls the dogleg levers back onto the unenergized position when the electromagnets are deenergized. In FIG. 5, there are only a few actuators shown, with two of the actuators shown in the forcing position. Many additional actuators (forcers) may be used depending upon the number of characters desired in a line and the spacing desired between the characters. For the average printing tabulator, 40 is the minimum number.

Referring now to FIG. 6, the planetary-type wheels 12 are shown positioned along a helix (skewed) path along the printing heads axis of rotation to compensate for the movement of the paper. The helix (skew) angle is adjusted to print out a straight line on the moving paper. The gap A-A' between the first and the last planetary-type wheel is not needed to allow the paper to advance one line space before the first type wheel is again in the print position. Each of the planetary-type wheels 12 may be provided with one or more additional rows of type faces 13b.

Referring to FIGS. 7, 8 and 9, wherein is shown a second type of forcing means 40 which may be used with the printer. Each individual actuator (forcer is identical in construction. Two conductive springs 201a and 20117 are affixed to one end to an insulating block 200. A rectangular metal coil 205 is electrically connected at one end to spring 201a. The opposite end of coil 205 is electrically connected to spring 2011:. An insulating member 210 insulates the coil body from spring 2011; except at its end. Electrical leads 220 are connected to springs 201a and 201b such that a current can be passed through the coil body. Thin insulating spacers 206, provided with notches 208 to clear coil joggle 209, and conducting areas 207a and 207b on one side only are positioned between each convolution of the coil 205. The conducting areas 207a and 20712 are electrically connected to the coil 205 and the entire assembly is then impregnated in a resin compound to rigid structure. Current flowing through the coil causes a magnetic field in each of the end films 207a and 207b. The magnetic fields are equal and opposite in the conductive films. Large permanent magnets 202 and 203 create a magnetic field which is created perpendicular to the field in the films. The created magnetic fields force the rigid structure created by the spacers 206 and the coil 205 to move outward from between the permanent magnets similar to a solenoid. A pad 221 fixed to the coils and spacers press the paper firmly against the type wheels. Removal or reversal of the current will move the forcer away from the paper. The same signal used to activate the forcer of FIG. 4 can be used to activate this forcer.

Referring now to FIGS. 10 and 11, wherein a printer having an oval track-type configuration is shown, an oval track 301a having flat side portions is formed in a top frame 320 and an identical oval track 301b is formed in a bottom frame 321. A plurality of printing heads 305 are guided around the oval path by the tracks. Each printing head may be pivotally linked to an adjacent head similar to a bicycle drive chain or it may be positioned abutting the adjacent head similar to ball bearings in a race. A drive wheel 304 having sprockets projections 300 thereon which mate with corresponding recesses 306 in the printing heads is rotated by a drive motor, not shown for purposes of clarity, to drive the printing heads along the tracks. The printing medium 30 is positioned adjacent the flat portions of the oval track with the forcing means 40 positioned behind the paper. A roller 302 guides the paper around a turn into position with the forcers 40. The type wheels 12 are rotatably mounted to the printing heads 300 by means of shaft 309. Drive gear 308 is affixed to the shaft and motor with a stationary gear 307 that passes around the outside of the oval track and is affixed to the upper frame 320. Because gear 307 is mounted to the outside of the track, no compensation is needed such as is required in the preceding embodiments. As the printing heads are moved around the track, the type wheels 12 are rotated in an opposite direction by the stationary gear 307, causing rotation of gear 308. The type wheels 12 may be either placed along a helix path or along a straight line as explained in the preceding embodiments. The paper advance is similar to the preceding embodiments except that the paper remains flat.

Referring now to FIG. 12, the shaft 309 in the embodiment of FIG. 11 is fairly long which increases the inertia of the typewheel assembly. For extremely high-speed printers, the type wheels must have a low inertia. This can be accomplished by providing a short shaft 310 and a type face 311 which is slanted at an inward angle so that the paper 30 can move into the printing area and bypass the stationary gear 307 and the upper frame 320. The roller 302, forcer, printing head and drive gear 308 are identical to those of FIG. 11.

The electronic control system shown in the preceding embodiments may be adapted to this embodiment by providing the identical relationship between the character type faces on the type wheels, and the character spaces on the recording sheet and the memory elements in the magnetic control system.

I claim:

1. A printer comprising in combination:

a. a cylindrical printing head rotatable about an axis of rotatron;

b. a plurality of type wheels, each having a respective type character repeated at equal intervals around the outer surface thereof, said wheels rotatably mounted around the periphery of said printing head on respective axes of rotation which are parallel to the axis of rotation of said printing head;

c. means for rotating said printing head in a first angular direction and for rotating said type wheels in a second angular direction opposite to said first angular direction;

d. paper support means for supporting paper along a curved surface in juxtaposition with at least two of said type wheels;

e. forcing means for pressing any paper supported by said paper support means into printing contact with the type characters on desired type wheels when said wheels are in a desired printing position with respect to said paper means; and

. paper drive means for advancing any paper supported by said paper support means in a direction parallel to the axes of rotation of said printing head and said type wheels.

2. The invention according to claim 1 wherein said type wheels have a second row of type faces positioned axially from said first named row for printing two lines of information simultaneously.

3. The invention according to claim 1 wherein said type wheels are skewed along the axis of rotation of the printing head and wherein said paper drive means advances said paper continuously such that a line of printing appears straight across said curved paper means.

4. The invention according to claim I wherein said forcing means is comprised of:

a. a plurality of individual actuators corresponding in number to the number of characters desired to be printed on a line of said paper, said actuators positioned one be hind each character on said paper; and

b. means for receiving a signal corresponding to the desired position of characters on said paper, said receiving means coupled to said individual actuators to activate individual actuators when the correct type wheel is in the correct character printing position with respect to said paper.

5. The invention according to claim 4 wherein each actuator is comprised of:

a. a substantially rectangular coil of wire;

b. a plurality of insulating spacers interposed between each coil of said wire;

c. a conductive film positioned at each end of said insulating spacers and in electrical contact with a corresponding coil of wire;

d. magnetic means positioned on opposite sides of said coil to create a magnetic field in which said conductive films lie;

e. spring means supporting said coil of wire in said magnetic means; and

f. means for passing a current through said coil in a desired direction to create a magnetic fields in said films to interact with the magnetic field of said magnetic means, thereby forcing said coil and insulating spacers to move.

6. The invention according to claim 1 and further comprising means for storing one or more lines of type character information; and means responsive to said stored information for activating said forcing means to print a corresponding type character at a predetermined position on said recording sheet.

7. The invention according to claim 1 in which said means for rotating said type wheels in a second angular direction opposite to said first angular direction comprises a planetary gear system interconnecting said type wheels and said means for rotating said printing wheel.

8. The invention according to claim 7 wherein said type wheels rotate at a linear surface velocity equal to but opposite to the linear surface velocity of said printing head. 

1. A printer comprising in combination: a. a cylindrical printing head rotatable about an axis of rotation; b. a plurality of type wheels, each having a respective type character repeated at equal intervals around the outer surface thereof, said wheels rotatably mounted around the periphery of said printing head on respective axes of rotation which are parallel to the axis of rotation of said printing head; c. means for rotating said printing head in a first angular direction and for rotating said type wheels in a second angular direction opposite to said first angular direction; d. paper support means for supporting paper along a curved surface in juxtaposition with at least two of said type wheels; e. forcing means for pressing any paper supported by said paper support means into printing contact with the type characters on desired type wheels when said wheels are in a desired printing position with respect to said paper means; and f. paper drive means for advancing any paper supported by said paper support means in a direction parallel to the axes of rotation of said printing head and said type wheels.
 2. The invention according to claim 1 wherein said type wheels have a second row of type faces positioned axially from said first named row for printing two lines of information simultaneously.
 3. The invention according to claim 1 wherein said type wheels are skewed along the axis of rotation of the printing head and wherein said paper drive means advances said paper continuously such that a line of printing appears straight across said curved paper means.
 4. The invention according to claim 1 wherein said forcing means is comprised of: a. a plurality of individual actuators corresponding in number to the number of characters desired to be printed on a line of said paper, said actuators positioned one behind each character on said paper; and b. means for receiving a signal corresponding to the desired position of characters on said paper, said receiving means coupled to said individual actuators to activate individual actuators when the correct type wheel is in the correct character printing position with respect to said paper.
 5. The invention according to claim 4 wherein each actuator is comprised of: a. a substantially rectangular coil of wire; b. a plurality of insulating spacers interposed between each coil of said wire; c. a conductive film positioned at each end of said insulating spacers and in electrical contact with a corresponding coil of wire; d. magnetic means positioned on opposite sides of said coil to create a magnetic field in which said conductive films lie; e. spring means supporting said coil of wire in said magnetic means; and f. means for passing a current through said coil in a desired direction to create a magnetic fields in said films to interact with the magnetic field of said magnetic means, thereby forcing said coil and insulating spacers to move.
 6. The invention according to claim 1 and further comprising means for storing one or more lines of type character information; and means responsive to said stored information for activating said forcing means to print a corresponding type character at a predetermined position on said recording sheet.
 7. The invention according to claim 1 in which said means for rotating said type wheels in a second angular direction opposite to said first angular direction comprises a planetary gear system interconnecting said type wheels and said means for rotating said printing wheel.
 8. The invention according to claim 7 wherein said type wheels rotate at a linear surface velocIty equal to but opposite to the linear surface velocity of said printing head. 